Quantifying suspended sediment dynamics under energetic nonlinear internal waves of depression

William Connellan Edge, Nicole L Jones, Matthew David Rayson, Gregory N. Ivey, Andrew Zulberti

Abstract: While nonlinear internal wave (NLIW) trains are known to influence near-sea bed suspended sediment dynamics, the mechanisms remain a topic of debate. We present near-sea bed observations of suspended sediment concentration $C$ and estimates of vertical sediment flux, at high vertical- and temporal-resolution, during trains of NLIW of depression. We quantify the contributions of vertical advection and turbulent mixing to $C$. Vertical advection was important during the leading wave, but the turbulent mixing flux was important over the entire wave train. The maximum vertical velocity was only weakly correlated with the maximum $C$, but the maximum horizontal speed squared was highly correlated with the maximum $C$. Boundary layer-induced turbulence was thus inferred to be the key driver of net vertical sediment flux over wave trains of this type. Estimating the maximum total horizontal speed (i.e. wave-induced plus background) is sufficient for modeling sediment vertical dynamics in shelf-scale modeling studies.

External IDs:doi:10.22541/essoar.175700062.29411175/v1